AIM: To investigate the effects of rat retinal ganglion cell (RGC) apoptosis on delayed rectifier K+currents (IK).METHODS:The retinas of 2~3 d newborn Sprague-Dawley rats were dissociated into cell suspension by trypsin digestion .The RGCs were cultured and divided into control group , pressure 0.5 h group, pressure 1 h group, pressure 1.5 h group and pressure 2 h group.The cells were cultured regularly for 6 d in control group , and the cells in other groups were cultured regularly for 6 d and gave pressure of 80 mmHg for 0.5 h, 1 h, 1.5 h and 2 h, respectively. The rhodamine 123 fluorescence from labeled RGC mitochondrion was detected by continuous wavelength multifunctional microplate detection instrument.The membrane capacitance (Cm) in different groups and IK in the pressure 1 h group were recorded from the RGCs by whole-cell patch-clamp technique .RESULTS:No difference of rhodamine 123 fluorescence in the RGC mitochondria between control group and pressure 0.5 h group was observed .Rhodamine 123 fluorescence in the other 3 groups was significantly lower than that in control group (P<0.05).No difference of the Cm between control group and pressure 0.5 h group was found, and the Cm in the other 3 groups was significantly lower than that in control group (P<0.05).The amplitudes of IK were higher than that in control group .At the test potential from -10 mV to 60 mV, the current density in pressure 1 h group was significantly higher than that in control group (P<0.05).The maximal conduc-tion ( Gmax ) in pressure 1 h group was significantly higher than that in control group .The voltage for IK channel half-activa-tion ( V1/2 ) in pressure 1 h group declined comparison with control group ( P<0.01 ) , and the k value had no significant difference between the 2 groups.CONCLUSION:Retinal ganglion cell apoptosis accompanies with delayed rectifier K +current enhancement .